The document discusses learning to play the theremin, an electronic musical instrument controlled without physical contact. It describes how the theremin was originally created as an accident while trying to build a motion detector. It then explains that the theremin uses two oscillators controlled by the position of the player's hands to produce pitch and volume, with closer positions producing higher pitches and louder sounds. While learning took time and was difficult, the document expresses that playing the theremin became a rewarding hobby for the author.